This invention relates generally to the manufacture and installation of countersink filler plugs, and, more particularly, to a device capable of securely holding such a filler plug adjacent a milling or grinding machine in order to control the specific amount of material to be removed from the filler plug prior to its installation within a countersunk hole.
There are many instances when it is highly desirable to fill countersunk holes which have been predrilled to accommodate specific type of fasteners. This is accomplished by the use of countersink filler plugs preferably made of aluminum. The utilization of such filler plugs is especially useful in the retro-fitting and repairing of fatigue or cracked skins on aircraft wings, doors, fuselages, etc. It is essential that unused countersunk holes be filled in order to insure the integrity of the outer surface of the aircraft in order to insure correct aerodynamic flow around the opening when the aircraft is in flight. In addition, there are situations when the filled in countersunk holes require enlarging and thereafter the installation of new countersink filler plugs.
It is current practice to fill such countersunk holes with aluminum plugs, of substantially the correct dimensions, which are glued, into the holes. In many instances, however, the inserted filler plugs are not flush with the skin surface after insertion thereof and therefore must be sanded or ground down to provide the required smooth aerodynamic surface. In the past this grinding or sanding operation took place with the filler plug in place and as a consequence during the grinding procedure many of the filler plugs become dislodged and flew out creating a safety hazard to surrounding personnel as well as substantially increasing the repair time. As a result, the filler plugs had to be reglued within the countersunk hole and resanded to the desired shape with the inherent possibility that they may flip out once again.
Such a procedure is not only costly, but also as pointed out hereinabove creates a substantial safety problem. Normally, the installation of approximately 200 countersink filler plugs with current procedures takes approximately 31/2 days to complete. It is therefore highly desirable to provide a system in which these filler plugs can be ground to their desired dimensions without creating a safety hazard and yet substantially decrease the amount of repair time.